Marker assemblies for labeling are well known, and especially the marking of shrink tubing to be applied to electrical wiring whereby identification can be made in the form of characters imprinted thereon. A widely used machine for imprinting characters is the typewriter, heretofore used to print upon marker assemblies comprised of heat shrink tubing held flat over cores or fillers inserted therein to substantially occupy the interior thereof preparatory to the imprinting of characters thereon. However, the insertion of cores and fillers has its limitations and special requirements in the typewriter construction. Firstly, the shrink tubing is limited in length, and secondly the typewriter platen must be specially adapted to the reception of the marker assembly with provision to drive the same. Therefore, it is a general object of this invention to provide a marker layup for reception into a typewriter without modification thereto and for the application of indicia upon the shrink tubing, to be used by technicians in permanently identifying electrical conductors.
This invention is concerned with the imprinting of indicia onto markers to be applied over the ends of electrical wiring that requires identification. It is thin walled (0.010 inch) cross linked polymer tubing or the like, with which this invention is concerned, and which is available in soft initially cured roll form of large cross-sectional diameter, and which is to be subjected to subsequent heat curing that reduces its diameter for constriction onto the wires to be identified, as circumstances require. The opacity and/or color of the tubing can vary, a white opaque tubing being widely employed. A problem arises in the imprinting of indicia onto such tubing, the roundness or cylindrical convexity making it difficult to imprint complete legible characters thereon. Heretofore, flattened cores or fillers have been inserted therein, but this process is restrictive whereas I have discovered that a partial shrink of the tubing while held flattened and through the application of controlled heat will harden the tubing sufficiently so that it will remain flat and pliable and conducive to being laminated for insertion into a typewriter in the usually intended fashion. With the present invention, continuous lengths of flattened shrink tubing can be produced, and cut to any length desired. In practice therefore, the shrink tubing is cut to a length to occupy the full width of a layup into which it is incorporated, said width being limited only by the length of the platen and/or typewriter carriage. In carrying out this invention, a plurality of flattened marker tubes are incorporated into a single layup.
The imprinting of indicia onto plastic material is widely employed, and typewriters are available for this purpose, utilizing ribbon or tape (film) with pressure transferable material thereon which is applied by pressure onto said plastic surface. These transfer materials are well known and are referred to generally as ink or carbon, or simply "carbon". It is an object therefore, to utilize such a film or carbon tape as it is supplied for ordinary typewriters. It is also an object to layup a traction sheet with one or more and preferably a plurality of shrink tubing sections held in alignment for imprinting utilizing conventional procedure therefor. With the present invention, the plurality of lengths of shrink tubing run from margin to margin, held in place to traction sheet. Therefore, the front face of the manifold is typed upon in the usual manner for correct reading, the characters being transferred directly from the typewriter ribbon or tape and onto the exposed shrink tubing. In practice, the tubing attachment can be perforated so that the tubing can be torn off and sequentially removed in lengths as required.
It is an object of this invention to provide a layup of the character referred to wherein available materials are employed, processed as described herein and cooperatively joined into a combination wherein a plurality of markers can be imprinted in an ordinary typewriter and subsequently removed and shrunk onto wires to be identified. The margins of the shrink tubing can be joined to the traction sheet by adhesive, releasable pressure adhesive of the type used for making removable tapes and the like, and all of which is sufficient to retain the integrity of the layup and to ensure proper alignment of the lengths of shrink tubing thereon.